You can get a Harman Crown XLS1000 for $189 delivered from Amazon. It is 350W x 2Ch into 4 ohms, which I think is plenty for your room.
Or the XLS1500 for $265, which is 525W x 2Ch into 4 ohms.
The 1010 sub is like $1200 retail new. I can tell you that $500 is well below actual dealer cost.
I have 5 SX-T2/R towers, which means 5 of the 1010 subs. Each sub is powered by my ATI AT3005 amp, which is 450WPC into 4 ohms x 5Ch.
I wouldn't trade my SX-1010 for any other subs, except for the SX-1212 subs.
As far as powered vs passive, I would never go back to powered subs. It is unequivocally passive sub + external amps for me.